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Viscous Fan hitting front of air duct

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mattmorgans

Member Since: 21 Sep 2023
Location: Bristol
Posts: 2

2013 Discovery 4 3.0 TDV6 XS Auto Corris Grey

Viscous Fan hitting front of air duct

Hi All,

I've just completed a front end rebuild (CoPart) of a Discovery 4 SDV6 and got a clear MOT, however, the MOT guy did mention that the viscous fan was hitting the front of the air box/duct when above 2500rpm.

I had already noticed it was close and had replaced the second hand fan I had purchased originally for the rebuild with another second hand fan as it was vibrating. I also replaced the bracket the fan mounts too as I thought this could possibly be causing the vibrating fan.

Have I just been unlucky and purchased two second hand fans that were dodgy or am I missing something. Maybe I should just bite the bullet and buy a new fan but worried it may still be tight to the front of the air duct.

Thanks in advance.

28th Sep 2024 12:31 pm

Norler

Member Since: 08 Oct 2024
Location: Oslo
Posts: 2

Hi,

Same problem here. However the problem occurred out of nowhere and fan hitting air box around 2800rpm.

First thought, the fan pulley bracket (fan bearing attached to engine). Replaced the original part with an aftermarket one.

Fan had lost a couple of chips so I cut it clean all around to balance it. This resulted in blades now approx 4cm away from air box at 0rpm. But now it hit the air box at 3000rpm. So this was not a fan pulley bracket problem.

I had to use the car and stayed well below 2800rpm for several weeks. But unfortunately i needed to pass another car and was probably at 3300rpm at one point. Suddenly the fan bracket bearing had a total failure and split. Resulting in the fan came off at full speed

Ordered a new aftermarket fan pulley bracket (another brand) and a new fan (and some other parts due to fan coming off). No luck. Still hitting the air box..

I then found another guy with an LR4 to check his. Same distance fan blade to airbox. He had no problems at all..

Confused I just had to make it work. New fan went off as it was not yet damaged. Then old fan was cut clean and installed to leave a new gap of 6cm. Resulting in no hitting at any rpm..

So.. What to make of all this.

1. Fan bearing bracket not the problem

2. Fan not the problem

3. Everything in engine bay installed physically correctly.

What could it possibly be.. I then one day thought maybe the fan spins to fast, way over the designed rpm. I had a person rev the car slow and steady up to 3000rpm. Saw the fan blades was bending towards the engine a huge amount. In my knowledge a fan should not go backwards when it blows backwards. It had to be overrevving. I contacted the fan manufacturer regarding the max designed rpm but got no reply.

This viscous fan has an electronic clutch to control the amount of slipping that is controlled by the car computer. As I've tried a brand new fan there just has to be something wrong with the computer signal. Either the wiring or the computer itself. Have not gotten any longer than this..

8th Oct 2024 9:43 am

Norler

Member Since: 08 Oct 2024
Location: Oslo
Posts: 2

Be aware..

Click image to enlarge

8th Oct 2024 10:23 am

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